U.S. patent number 4,137,909 [Application Number 05/820,838] was granted by the patent office on 1979-02-06 for medical electrode.
This patent grant is currently assigned to NDM Corporation. Invention is credited to Ernet T. Hix.
United States Patent |
4,137,909 |
Hix |
February 6, 1979 |
**Please see images for:
( Certificate of Correction ) ** |
Medical electrode
Abstract
A medical electrode for attachment to the skin of a patient has
a cup member forming a cavity for containing an electroylyte. The
cup member has a base portion which is movable inwardly of the cup
member so as to contract the interior volume of the cavity and in
so doing displace the electrolyte outwardly of the cup member for
contact to the skin of a patient. In a modification, the
configuration of the base of the cup member allows an electrode
conductor to be supported out of contact with the electrolyte until
the base portion is moved to displace electrolyte outwardly of the
cup member.
Inventors: |
Hix; Ernet T. (Dayton, OH) |
Assignee: |
NDM Corporation (Dayton,
OH)
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Family
ID: |
25231844 |
Appl.
No.: |
05/820,838 |
Filed: |
August 1, 1977 |
Current U.S.
Class: |
600/392; 600/394;
600/397 |
Current CPC
Class: |
A61B
5/25 (20210101); A61B 2562/0215 (20170801); A61B
2562/0217 (20170801) |
Current International
Class: |
A61B
5/0408 (20060101); A61B 005/04 () |
Field of
Search: |
;128/2.6E,2.1R,404,410,411,416-418,DIG.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2152808 |
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Apr 1973 |
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DE |
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2208653 |
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Apr 1973 |
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DE |
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2548805 |
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May 1977 |
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DE |
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Primary Examiner: Cohen; Lee S.
Attorney, Agent or Firm: Dybvig & Dybvig
Claims
Having thus described my invention, I claim:
1. In a medical electrode of the type adapted to be adhered to the
skin, said electrode having means defining a cavity receiving an
electrolyte and having an opening adapted to open to the skin, and
having conductive means at the base of said cavity for allowing
external connection to said electrolyte, the improvement wherein
said means defining a cavity comprises a wall surrounding said base
and said electrolyte and means supporting said base and said
conductive means in a first position rearward with respect to said
wall for an expanded volume of said cavity and for movement to a
second position inwardly of said wall to reduce the volume of said
cavity and thus press said electrolyte outwardly of said cavity
through said opening for engagement with and compression against
the skin, said means supporting said base resisting return of said
base from said second position to said first position.
2. The improvement of claim 1 wherein said means supporting said
base comprises a first arch portion integrally attached to said
surrounding wall and arching inwardly of said cavity and a second
arch portion arching rearwardly of said cavity from said first arch
portion and integrally joined to said base, the direction in which
said second arch portion arches reversing upon movement of said
base toward said second position, said reversing of the direction
in which said second arch portion arches causing said second arch
portion to resist a return of said base to said first position.
3. The improvement of claim 2 wherein said first and second arch
portions cooperate to support said electrolyte remotely from said
conductive means in said first position.
4. The improvement of claim 1 wherein said means supporting said
base and said conductive means in a first position supports said
conductive means remotely from said electrolyte and, in said second
position, supports said conductive means in contact with said
electrolyte.
5. The improvement of claim 1 wherein said base, said surrounding
wall and said means supporting said base are integrally formed, and
said conductive means passes through said base.
6. In a medical electrode of the type adapted to be adhered to the
skin, said electrode having means defining a cavity receiving an
electrolyte and having an opening adapted to open to the skin, and
having conductive means affixed to the base of said cavity for
allowing external connection to said electrolyte, the improvement
wherein said means defining a cavity comprises a wall surrounding
said base and said electrolyte, and means joined to said wall and
to said base for supporting said base in a first position remote
from said skin and, upon application of a pressure to said base,
shifting said base to a second position closer to said skin to
reduce the volume of said cavity and thus press said electrolyte
through said opening against the skin, and means joined to said
wall and to said base having a curvature which reverses upon
movement of said base from said first position to said second
position so that said means joined to said wall and to said base
resists return of said base from said second position to said first
position.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to medical electrodes for use in contact
with the skin of a patient and to means included in the electrode
construction for transferring a skin-contacting electrolyte sponge
between storage and usage positions.
2. Prior Art
U.S. Pat. No. 3,701,346 illustrates a medical electrode housing an
oversized electrolyte sponge protected by a removable cover. To
prevent squeezing of electrolyte from the sponge, the protective
cover has an oversized cavity which receives the sponge without
premature squeezing of the sponge during assembly and storage.
Following removal of the protective cover, the electrolyte sponge
is exposed to the pressure of the patient's skin, which squeezes
the sponge, thus assuring a liberal wetting of the patient's skin
with electrolyte from the sponge. U.S. Pat. Nos. 3,805,769 and
3,982,529 illustrate other techniques for providing electrolyte at
the skin surface when the electrode is in use.
An object of the present invention is to provide a new and improved
medical electrode and, more particularly, a medical electrode
having a cup which is actuable so as to transfer electrolyte means
from a storage position within the cup to an outwardly displaced
position for effective contact with the skin.
SUMMARY OF THE INVENTION
In the present invention, an electrode cup for receipt of
electrolyte means such as an electrolyte-soaked sponge is formed
with a base actuable from a first position in which the base forms
an outer wall of the cup to a second position in which the base is
depressed inwardly of the cup, the actuation of the base from the
first position to the second position requiring a manual effort and
displacing the electrolyte sponge outwardly from a storage chamber
of the cup so as to produce firm contact between the electrolyte
sponge and the skin of a patient. In a modification, a conductor
attached to the base of the electrode cup is initially supported
remotely from the electrolyte means within the cup so as to prevent
contact between electrolyte and the conductor until after the base
portion has been actuated to press the electrolyte means against
the skin of a patient and to press the conductor into firm
engagement with the electrolyte.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view illustrating a medical
electrode in accordance with the present invention.
FIG. 2 is a transverse section view of the assembled electrode.
FIG. 3 is a section view analogous to that of FIG. 2, illustrating
the electrode after actuation for contact of electrolyte to the
skin of a patient.
FIG. 4 is a section view analogous to FIG. 2, illustrating a
modification.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, the drawings illustrate a medical electrode 10
in which an annulus of elastic foam sponge material 12 has a
central aperture 13 for receiving the closed end of a cup member
16. A circlet 14 of a flexible plastic material, such as a vinyl
plastic, secured by adhesive 23 lies over the closed end of the cup
member 16 and closes the aperture 13 in the foam sponge 12.
The members 12, 14 and 16 are secured in assembled relation by
means of a two-part snap fastener comprising a male part 18 within
the cup member 16 and a female part 20 into which the male part 18
has been pressed in conventional fashion, the male part having an
eyelet or stem 19 passing through an aperture 17 located in the
base 22 of the cup member 16 and an aperture 15 located in the
center of the circlet 14.
The cup member 16 houses an electrolyte sponge 32, which is
preferably an open cell foam plastic and which is saturated prior
to assembly of the electrode with an electrolyte 33.
The foam sponge annulus 12 has adhesive 24 applied to its lower
surface, as appears in FIG. 2, and such adhesive is protected
during storage and shipment by a layer of release paper 26. The
release paper 26 has a central opening 27 of the same size as the
aforementioned opening 13 to receive the closed end of the cup
member 16.
The release paper 26 also has an incision 28, whose diameter
corresponds to the outside diameter of a flange 42 projecting
outwardly from the cup member 16. As best appears in FIG. 2, the
release paper 26 has an included annulus 30 which becomes trapped
between the flange 42 of the cup member 16 and the sponge annulus
12. Beyond the diameter of the annulus 30, the release paper 26
extends outwardly in the form of a square sheet whose corners 29
project beyond the outside diameter of the sponge annulus 12.
The electrolyte 33 residing in the sponge 32 is protected from dust
and from a premature compression of the sponge, such as would
extrude electrolyte from the sponge, by means of a protective cover
34 having an integral annular wall 36 which supports a panel 38
recessed into the cover 34 so as to accommodate the shape of the
cup member 16. Thus, as appears in FIG. 2, the wall 36 receives the
outside margin of the aforementioned flange 42, and the cover 34 is
provided with an outwardly projecting flange 39 affixed to the
release paper 26 outside the incision 28 by adhesive tacks 40, such
as appear in FIG. 1.
The arrangement is such that the protective cover 34 can protect
the sponge 32 from damage until immediately prior to the use of the
electrode, whereupon the corners 29 of the release paper 26 can be
pulled away from the adhesive surface of the sponge annulus 12. As
the outer margin of the release paper is pulled away from the
sponge annulus 12, it carries with it the adhesively tacked
protective cover 34. However, due to the presence of the
aforementioned incision 28, the included annulus 30 remains in
adhesive contact with the sponge annulus 12 because it is trapped
between the outer flange 42 of the cup member 16 and the sponge
annulus 12.
Referring in greater detail to the cup member 16, it can be noted
that the cup member includes an annular wall 46 supported inwardly
of the aforementioned flange 42 by means of a wall portion 43
forming a channel 44.
The wall 46 joins to the base 22 by means of a first arch 48
curving downwardly or forwardly toward the mouth of the cup member.
The first arch 48 is followed by a second arch 50 curving upwardly
or rearwardly and then radially inwardly to integrally merge with
the base 22. The arches 48 and 50 encircle the male snap fastener
part 18.
When the snap fastener is pressed downwardly, as it appears in FIG.
2, the arch 50 opens as the arch 48 closes to permit the base 22 to
drop downwardly to a new position disposed deeply within the
annular wall 46. This downward movement reverses the curvature of
the arch 50, and the inward bias of the arch 48 resists an upward
return of the base 22.
The nature of the reversal that occurs in the arch 50 can be better
visualized after a comparison of FIG. 2, which shows the electrode
assembly before the female snap fastener 20 has been manually
pressed downwardly, and FIG. 3, which shows the approximate cross
sectional appearance of the cup member 16 after the female snap
fastener 20 has been pressed downwardly a sufficient distance to
effect a reversal of the arch 50.
A further comparison of FIGS. 2 and 3 will show that the axial
dimension of the wall 46 of the cup 16 was sized to accommodate the
axial dimension of the electrolyte sponge 32 without compressing
that sponge. However, when the female snap fastener member 20 is
pressed downwardly to effect the transition illustrated in FIG. 3,
the interior volume of the cup member 16 is shrunk substantially
with the result that the male snap fastener part 18 presses firmly
against the sponge 32 and presses that sponge firmly against the
patient's skin, as schematically illustrated in FIG. 3.
As is common in the use of medical electrodes such as described,
the female snap fastener 20 is engaged by a detachable fastener 56
having a conductor 58 extending therefrom for the purpose of
conducting electrical signals from the skin of the patient to
appropriate electrocardiograph equipment. As will be apparent to
those skilled in the art, attachment of the fastener 56 to the
female snap fastener 20 may be accomplished before actuation of the
base of the electrode cup downwardly toward the skin, at the same
time, or at a later time, depending upon the desires of the
technician who applies the electrodes.
It is known that many electrode materials, such as the metal
silver, undergo chemical reactions with the electrolyte,
particularly when first contacted to the electrolyte. For this
reason, electrodes which are prefilled with electrolyte have become
popular. The prefilling necessitates that the electrode material
will have been in contact with the electrolyte for substantial
periods of time before applied to the skin of a patient. During
such periods of time, the silver is thought to be passivated with
respect to the electrolyte; and, by the time the electrode is
contacted to the skin of the patient, passivation will be complete
so that signal noises attributable to reactions occurring between
the electrolyte and the conductor material are minimized.
Other metals, particularly zinc, are readily soluble as ions in an
appropriately selected electrolyte, such as silver chloride, and
require no passivation. In and of itself, this is an advantageous
feature. However, in the case of prefilled electrodes, the
continuing dissociation or ionization of the zinc or other readily
soluble metal contacted by the electrolyte necessitates that the
electrode conductor include a sufficient amount of the zinc or
other metal so as not to be fully ionized during storage of the
electrode.
Alternatively, it is desirable that the zinc or other readily
soluble conductive material be stored out of contact with the
electrolyte and permitted to contact the electrolyte only
immediately before the electrode is to be used. This enables
construction of electrodes having only minimal amounts of a
conductor material which can be readily soluble when contacted by
the electrolyte.
In the modification illustrated in FIG. 4, structural features
substantially the same as previously described in reference to the
preferred embodiment have been identified with the same reference
numbers as employed in discussing the preferred embodiment, the
suffix "a" being used in association with the reference numbers to
distinguish the structural features of the modification from those
of the preferred embodiment.
As was true of the preferred embodiment, the cup 16a of the
modification includes an annular wall 46a supporting a base 22a.
The base 22a is surrounded by a downwardly curved arch 50a followed
outwardly by an upwardly directed arch 48a.
In marked departure from the preferred embodiment, the arches 48a
and 50a are so sized relative to the snap fastener part 18a and the
electrolyte sponge 32a that the sponge 32a will not contact the
fastener part 18a during storage of the electrode assembly.
Except for the foregoing difference, the modification of FIG. 4 may
be constructed and assembled in the same manner as has been
described in reference to the preferred embodiment.
The actuation of the modification is essentially as has been
described in connection with the preferred embodiment. Thus, by
exerting a downward pressure on the snap fastener part 20a, the
part 18a, which is initially out of contact with the electrolyte
sponge 32a, is pushed downwardly into the cup 16a, causing the snap
fastener part 18a to engage the electrolyte sponge 32a as that
sponge is advanced outwardly of the cup 16a and pressed against the
skin of a patient.
This modification offers the advantage that the snap fastener part
18a may be a relatively soluble metal, such as zinc, or may be a
composite plastic material including zinc or the like. Prior to use
of the modification, the arch 50a operates to maintain a separation
between the male snap fastener part 18a and the electrolyte sponge
32a. This protects the readily soluble metal comprising the snap
fastener part 18a from a premature dissolution into the electrolyte
of the sponge 32a. Prior to the time electrocardiograph traces are
to be taken, the snap fastener part 20a is actuated downwardly to
cause the snap fastener part 18a to contact the electrolyte of the
sponge 32a.
It will be noted that both of the cup members 16 and 16a disclosed
in the present application are of a relatively low profile
configuration. The present invention offers the advantage, however,
that, in each of the two cup configurations described, the snap
fastener part 20, which initially protrudes upwardly from the base
of the cup, is pressed into the cup upon actuation of the snap
fastener to transfer the electrolyte sponge from within the cup to
an outwardly extended position bearing against the skin of the
patient, thus further reducing the electrode profile. A variety of
materials may be used to form the cup members 16 and 16a, examples
being vinyl plastic, linear polyethylene and cellulose acetate
butyrate.
Although the preferred embodiments of the present invention have
been described, it will be understood that various changes may be
made within the scope of the appended claims.
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